<!DOCTYPE html>
<html>
<head>
<script>

function boom()
{
  var frameRoot = document.getElementById("f").contentDocument.documentElement;
  var marquee = frameRoot.getElementsByTagName("marquee")[0];
  marquee.__proto__ = [];
  frameRoot.appendChild(marquee);
}

</script>
</head>

<body onload="boom();">

<iframe id="f" src="data:application/xhtml+xml,<html xmlns='http://www.w3.org/1999/xhtml'><body><marquee></marquee></body></html>"></iframe>

</body>
</html>
